forked from OSchip/llvm-project
430 lines
15 KiB
C++
430 lines
15 KiB
C++
// SimpleSValuator.cpp - A basic SValuator ------------------------*- C++ -*--//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines SimpleSValuator, a basic implementation of SValuator.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Analysis/PathSensitive/SValuator.h"
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#include "clang/Analysis/PathSensitive/GRState.h"
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#include "llvm/Support/Compiler.h"
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using namespace clang;
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namespace {
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class VISIBILITY_HIDDEN SimpleSValuator : public SValuator {
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protected:
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virtual SVal EvalCastNL(NonLoc val, QualType castTy);
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virtual SVal EvalCastL(Loc val, QualType castTy);
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public:
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SimpleSValuator(ValueManager &valMgr) : SValuator(valMgr) {}
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virtual ~SimpleSValuator() {}
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virtual SVal EvalMinus(NonLoc val);
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virtual SVal EvalComplement(NonLoc val);
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virtual SVal EvalBinOpNN(const GRState *state, BinaryOperator::Opcode op,
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NonLoc lhs, NonLoc rhs, QualType resultTy);
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virtual SVal EvalBinOpLL(BinaryOperator::Opcode op, Loc lhs, Loc rhs,
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QualType resultTy);
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virtual SVal EvalBinOpLN(const GRState *state, BinaryOperator::Opcode op,
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Loc lhs, NonLoc rhs, QualType resultTy);
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};
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} // end anonymous namespace
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SValuator *clang::CreateSimpleSValuator(ValueManager &valMgr) {
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return new SimpleSValuator(valMgr);
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}
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//===----------------------------------------------------------------------===//
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// Transfer function for Casts.
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//===----------------------------------------------------------------------===//
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SVal SimpleSValuator::EvalCastNL(NonLoc val, QualType castTy) {
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bool isLocType = Loc::IsLocType(castTy);
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if (nonloc::LocAsInteger *LI = dyn_cast<nonloc::LocAsInteger>(&val)) {
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if (isLocType)
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return LI->getLoc();
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ASTContext &Ctx = ValMgr.getContext();
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// FIXME: Support promotions/truncations.
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if (Ctx.getTypeSize(castTy) == Ctx.getTypeSize(Ctx.VoidPtrTy))
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return val;
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return UnknownVal();
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}
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if (const SymExpr *se = val.getAsSymbolicExpression()) {
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ASTContext &Ctx = ValMgr.getContext();
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QualType T = Ctx.getCanonicalType(se->getType(Ctx));
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if (T == Ctx.getCanonicalType(castTy))
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return val;
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// FIXME: Remove this hack when we support symbolic truncation/extension.
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// HACK: If both castTy and T are integers, ignore the cast. This is
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// not a permanent solution. Eventually we want to precisely handle
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// extension/truncation of symbolic integers. This prevents us from losing
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// precision when we assign 'x = y' and 'y' is symbolic and x and y are
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// different integer types.
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if (T->isIntegerType() && castTy->isIntegerType())
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return val;
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return UnknownVal();
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}
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if (!isa<nonloc::ConcreteInt>(val))
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return UnknownVal();
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// Only handle casts from integers to integers.
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if (!isLocType && !castTy->isIntegerType())
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return UnknownVal();
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llvm::APSInt i = cast<nonloc::ConcreteInt>(val).getValue();
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i.setIsUnsigned(castTy->isUnsignedIntegerType() || Loc::IsLocType(castTy));
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i.extOrTrunc(ValMgr.getContext().getTypeSize(castTy));
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if (isLocType)
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return ValMgr.makeIntLocVal(i);
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else
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return ValMgr.makeIntVal(i);
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}
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SVal SimpleSValuator::EvalCastL(Loc val, QualType castTy) {
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// Casts from pointers -> pointers, just return the lval.
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//
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// Casts from pointers -> references, just return the lval. These
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// can be introduced by the frontend for corner cases, e.g
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// casting from va_list* to __builtin_va_list&.
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//
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if (Loc::IsLocType(castTy) || castTy->isReferenceType())
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return val;
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// FIXME: Handle transparent unions where a value can be "transparently"
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// lifted into a union type.
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if (castTy->isUnionType())
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return UnknownVal();
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assert(castTy->isIntegerType());
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unsigned BitWidth = ValMgr.getContext().getTypeSize(castTy);
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if (!isa<loc::ConcreteInt>(val))
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return ValMgr.makeLocAsInteger(val, BitWidth);
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llvm::APSInt i = cast<loc::ConcreteInt>(val).getValue();
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i.setIsUnsigned(castTy->isUnsignedIntegerType() || Loc::IsLocType(castTy));
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i.extOrTrunc(BitWidth);
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return ValMgr.makeIntVal(i);
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}
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//===----------------------------------------------------------------------===//
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// Transfer function for unary operators.
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//===----------------------------------------------------------------------===//
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SVal SimpleSValuator::EvalMinus(NonLoc val) {
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switch (val.getSubKind()) {
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case nonloc::ConcreteIntKind:
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return cast<nonloc::ConcreteInt>(val).evalMinus(ValMgr);
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default:
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return UnknownVal();
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}
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}
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SVal SimpleSValuator::EvalComplement(NonLoc X) {
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switch (X.getSubKind()) {
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case nonloc::ConcreteIntKind:
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return cast<nonloc::ConcreteInt>(X).evalComplement(ValMgr);
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default:
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return UnknownVal();
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}
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}
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//===----------------------------------------------------------------------===//
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// Transfer function for binary operators.
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//===----------------------------------------------------------------------===//
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static BinaryOperator::Opcode NegateComparison(BinaryOperator::Opcode op) {
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switch (op) {
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default:
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assert(false && "Invalid opcode.");
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case BinaryOperator::LT: return BinaryOperator::GE;
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case BinaryOperator::GT: return BinaryOperator::LE;
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case BinaryOperator::LE: return BinaryOperator::GT;
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case BinaryOperator::GE: return BinaryOperator::LT;
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case BinaryOperator::EQ: return BinaryOperator::NE;
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case BinaryOperator::NE: return BinaryOperator::EQ;
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}
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}
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// Equality operators for Locs.
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// FIXME: All this logic will be revamped when we have MemRegion::getLocation()
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// implemented.
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static SVal EvalEquality(ValueManager &ValMgr, Loc lhs, Loc rhs, bool isEqual,
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QualType resultTy) {
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switch (lhs.getSubKind()) {
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default:
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assert(false && "EQ/NE not implemented for this Loc.");
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return UnknownVal();
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case loc::ConcreteIntKind: {
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if (SymbolRef rSym = rhs.getAsSymbol())
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return ValMgr.makeNonLoc(rSym,
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isEqual ? BinaryOperator::EQ
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: BinaryOperator::NE,
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cast<loc::ConcreteInt>(lhs).getValue(),
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resultTy);
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break;
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}
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case loc::MemRegionKind: {
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if (SymbolRef lSym = lhs.getAsLocSymbol()) {
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if (isa<loc::ConcreteInt>(rhs)) {
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return ValMgr.makeNonLoc(lSym,
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isEqual ? BinaryOperator::EQ
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: BinaryOperator::NE,
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cast<loc::ConcreteInt>(rhs).getValue(),
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resultTy);
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}
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}
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break;
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}
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case loc::GotoLabelKind:
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break;
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}
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return ValMgr.makeTruthVal(isEqual ? lhs == rhs : lhs != rhs, resultTy);
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}
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SVal SimpleSValuator::EvalBinOpNN(const GRState *state,
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BinaryOperator::Opcode op,
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NonLoc lhs, NonLoc rhs,
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QualType resultTy) {
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// Handle trivial case where left-side and right-side are the same.
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if (lhs == rhs)
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switch (op) {
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default:
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break;
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case BinaryOperator::EQ:
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case BinaryOperator::LE:
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case BinaryOperator::GE:
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return ValMgr.makeTruthVal(true, resultTy);
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case BinaryOperator::LT:
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case BinaryOperator::GT:
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case BinaryOperator::NE:
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return ValMgr.makeTruthVal(false, resultTy);
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}
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while (1) {
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switch (lhs.getSubKind()) {
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default:
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return UnknownVal();
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case nonloc::LocAsIntegerKind: {
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Loc lhsL = cast<nonloc::LocAsInteger>(lhs).getLoc();
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switch (rhs.getSubKind()) {
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case nonloc::LocAsIntegerKind:
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return EvalBinOpLL(op, lhsL, cast<nonloc::LocAsInteger>(rhs).getLoc(),
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resultTy);
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case nonloc::ConcreteIntKind: {
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// Transform the integer into a location and compare.
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ASTContext& Ctx = ValMgr.getContext();
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llvm::APSInt i = cast<nonloc::ConcreteInt>(rhs).getValue();
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i.setIsUnsigned(true);
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i.extOrTrunc(Ctx.getTypeSize(Ctx.VoidPtrTy));
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return EvalBinOpLL(op, lhsL, ValMgr.makeLoc(i), resultTy);
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}
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default:
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switch (op) {
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case BinaryOperator::EQ:
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return ValMgr.makeTruthVal(false, resultTy);
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case BinaryOperator::NE:
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return ValMgr.makeTruthVal(true, resultTy);
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default:
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// This case also handles pointer arithmetic.
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return UnknownVal();
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}
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}
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}
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case nonloc::SymExprValKind: {
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// Logical not?
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if (!(op == BinaryOperator::EQ && rhs.isZeroConstant()))
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return UnknownVal();
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const SymExpr *symExpr =
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cast<nonloc::SymExprVal>(lhs).getSymbolicExpression();
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// Only handle ($sym op constant) for now.
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if (const SymIntExpr *symIntExpr = dyn_cast<SymIntExpr>(symExpr)) {
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BinaryOperator::Opcode opc = symIntExpr->getOpcode();
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switch (opc) {
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case BinaryOperator::LAnd:
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case BinaryOperator::LOr:
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assert(false && "Logical operators handled by branching logic.");
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return UnknownVal();
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case BinaryOperator::Assign:
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case BinaryOperator::MulAssign:
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case BinaryOperator::DivAssign:
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case BinaryOperator::RemAssign:
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case BinaryOperator::AddAssign:
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case BinaryOperator::SubAssign:
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case BinaryOperator::ShlAssign:
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case BinaryOperator::ShrAssign:
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case BinaryOperator::AndAssign:
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case BinaryOperator::XorAssign:
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case BinaryOperator::OrAssign:
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case BinaryOperator::Comma:
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assert(false && "'=' and ',' operators handled by GRExprEngine.");
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return UnknownVal();
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case BinaryOperator::PtrMemD:
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case BinaryOperator::PtrMemI:
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assert(false && "Pointer arithmetic not handled here.");
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return UnknownVal();
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case BinaryOperator::Mul:
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case BinaryOperator::Div:
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case BinaryOperator::Rem:
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case BinaryOperator::Add:
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case BinaryOperator::Sub:
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case BinaryOperator::Shl:
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case BinaryOperator::Shr:
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case BinaryOperator::And:
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case BinaryOperator::Xor:
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case BinaryOperator::Or:
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// Not handled yet.
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return UnknownVal();
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case BinaryOperator::LT:
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case BinaryOperator::GT:
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case BinaryOperator::LE:
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case BinaryOperator::GE:
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case BinaryOperator::EQ:
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case BinaryOperator::NE:
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opc = NegateComparison(opc);
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assert(symIntExpr->getType(ValMgr.getContext()) == resultTy);
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return ValMgr.makeNonLoc(symIntExpr->getLHS(), opc,
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symIntExpr->getRHS(), resultTy);
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}
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}
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}
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case nonloc::ConcreteIntKind: {
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if (isa<nonloc::ConcreteInt>(rhs)) {
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const nonloc::ConcreteInt& lhsInt = cast<nonloc::ConcreteInt>(lhs);
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return lhsInt.evalBinOp(ValMgr, op, cast<nonloc::ConcreteInt>(rhs));
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}
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else {
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// Swap the left and right sides and flip the operator if doing so
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// allows us to better reason about the expression (this is a form
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// of expression canonicalization).
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NonLoc tmp = rhs;
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rhs = lhs;
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lhs = tmp;
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switch (op) {
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case BinaryOperator::LT: op = BinaryOperator::GT; continue;
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case BinaryOperator::GT: op = BinaryOperator::LT; continue;
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case BinaryOperator::LE: op = BinaryOperator::GE; continue;
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case BinaryOperator::GE: op = BinaryOperator::LE; continue;
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case BinaryOperator::EQ:
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case BinaryOperator::NE:
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case BinaryOperator::Add:
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case BinaryOperator::Mul:
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continue;
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default:
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return UnknownVal();
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}
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}
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}
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case nonloc::SymbolValKind: {
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nonloc::SymbolVal *slhs = cast<nonloc::SymbolVal>(&lhs);
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SymbolRef Sym = slhs->getSymbol();
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// Does the symbol simplify to a constant? If so, "fold" the constant
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// by setting 'lhs' to a ConcreteInt and try again.
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if (Sym->getType(ValMgr.getContext())->isIntegerType())
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if (const llvm::APSInt *Constant = state->getSymVal(Sym)) {
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// The symbol evaluates to a constant. If necessary, promote the
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// folded constant (LHS) to the result type.
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BasicValueFactory &BVF = ValMgr.getBasicValueFactory();
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const llvm::APSInt &lhs_I = BVF.Convert(resultTy, *Constant);
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lhs = nonloc::ConcreteInt(lhs_I);
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// Also promote the RHS (if necessary).
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// For shifts, it necessary promote the RHS to the result type.
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if (BinaryOperator::isShiftOp(op))
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continue;
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// Other operators: do an implicit conversion. This shouldn't be
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// necessary once we support truncation/extension of symbolic values.
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if (nonloc::ConcreteInt *rhs_I = dyn_cast<nonloc::ConcreteInt>(&rhs)){
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rhs = nonloc::ConcreteInt(BVF.Convert(resultTy, rhs_I->getValue()));
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}
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continue;
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}
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if (isa<nonloc::ConcreteInt>(rhs)) {
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return ValMgr.makeNonLoc(slhs->getSymbol(), op,
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cast<nonloc::ConcreteInt>(rhs).getValue(),
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resultTy);
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}
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return UnknownVal();
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}
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}
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}
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}
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SVal SimpleSValuator::EvalBinOpLL(BinaryOperator::Opcode op, Loc lhs, Loc rhs,
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QualType resultTy) {
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switch (op) {
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default:
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return UnknownVal();
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case BinaryOperator::EQ:
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case BinaryOperator::NE:
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return EvalEquality(ValMgr, lhs, rhs, op == BinaryOperator::EQ, resultTy);
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case BinaryOperator::LT:
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case BinaryOperator::GT:
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// FIXME: Generalize. For now, just handle the trivial case where
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// the two locations are identical.
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if (lhs == rhs)
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return ValMgr.makeTruthVal(false, resultTy);
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return UnknownVal();
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}
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}
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SVal SimpleSValuator::EvalBinOpLN(const GRState *state,
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BinaryOperator::Opcode op,
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Loc lhs, NonLoc rhs, QualType resultTy) {
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// Special case: 'rhs' is an integer that has the same width as a pointer and
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// we are using the integer location in a comparison. Normally this cannot be
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// triggered, but transfer functions like those for OSCommpareAndSwapBarrier32
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// can generate comparisons that trigger this code.
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// FIXME: Are all locations guaranteed to have pointer width?
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if (BinaryOperator::isEqualityOp(op)) {
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if (nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs)) {
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const llvm::APSInt *x = &rhsInt->getValue();
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ASTContext &ctx = ValMgr.getContext();
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if (ctx.getTypeSize(ctx.VoidPtrTy) == x->getBitWidth()) {
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// Convert the signedness of the integer (if necessary).
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if (x->isSigned())
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x = &ValMgr.getBasicValueFactory().getValue(*x, true);
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return EvalBinOpLL(op, lhs, loc::ConcreteInt(*x), resultTy);
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}
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}
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}
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// Delegate pointer arithmetic to the StoreManager.
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return state->getStateManager().getStoreManager().EvalBinOp(state, op, lhs,
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rhs, resultTy);
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}
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